Air coming out of the vents doesn't mean every part of the AC is working. Controls, airflow, refrigerant problems and failed components can all be part of an investigation.
Tell the shop what the system is doing instead of booking a repair you've guessed it needs. “Not cooling” is a symptom. “Needs refrigerant” is a conclusion the technician has to check.

Is air coming from the vents? Can you hear the outdoor unit from a safe location? Is no part of the house cooling, or are some rooms staying warmer than others?
Mention when it began, the thermostat display, recent work and any outage. Send a photo of an accessible equipment label if you can. You don't need to open covers or touch pipes to prepare for the call.
A whole house cooling failure and a longstanding warm bedroom deserve different descriptions. Include both if both are happening.
Carrier describes several possible causes of poor cooling, including airflow restrictions, controls, dirty coils, refrigerant leaks and component problems. A list of possibilities doesn't diagnose your equipment.
Ask the technician to explain the condition found and how the proposed work addresses it. If the recommendation involves refrigerant, a component or an airflow change, have that work named in the quote.
Also ask what gets checked afterward and whether another visit or test remains. You should know whether the price is for the investigation, a specified repair or both.
Ask why the company recommends it and whether repair is an option. Get the limits of a repair explained alongside the full replacement work.
Our repair or replace guide covers that decision. The replacement quote guide covers equipment, connected work and permits.
A service appointment doesn't address an immediate heat emergency. Seek emergency help if someone is in immediate danger or has severe symptoms.
For the appointment itself, confirm the visit charge and diagnostic work before booking. Send any recent reports so the technician knows what has already been checked or changed.